Everyone occasionally experiences a temporary feeling of numbness, tingling, and loss of sensation when a limb "goes to sleep." These sensations are caused by stretching of, or pressure on, a nerve and usually last for only a few minutes.

Numbness or tingling in any part of the body may also be a side effect of certain prescription drugs, especially medications to treat cancer and psychiatric disorders. The numbness usually abates when the drug is stopped or the dosage reduced. In some cases, numbness and loss of sensation can be symptoms of a medical problem, or a warning sign of a serious situation such as a stroke.

Causes of numbness and loss of sensation

Carpal tunnel syndromeIn this condition, pressure on the median nerve in the wrist causes tingling sensations and numbness in the fingers. It often affects both hands and may begin suddenly or come on gradually. The source of the pressure may be an injury, or a job or hobby that requires keeping the wrist in a bent position. Rheumatoid arthritis and gout can cause soft tissues to swell and compress the median nerve. Other possible causes include swelling of the hands due to pregnancy or use of birth control pills, diabetes, a tumor of the median nerve, thyroid disease, and acromegaly, a rare disease characterized by abnormal bone growth.

DiabetesDiabetes, a metabolic disease in which the body fails to produce or properly utilize insulin, often causes nerve damage, resulting in tingling or numbness in the legs, feet, or fingers. This kind of nerve damage is usually a late manifestation of Type 1, or juvenile diabetes. In Type 2, or adult-onset, diabetes, however, nerve damage may be among the early symptoms.

Guillain-Barre syndromeThis disease causes nerve inflammation and damage throughout the body. The disease typically begins with weakness, sensations of tingling, and numbness of the legs. As the nerve damage moves upward, more parts of the body are affected. Some muscles may become

Leg numbness is often a temporary sensation.

paralyzed, and artificial respiration is sometimes needed.

Multiple sclerosisMultiple sclerosis is a progressive chronic disease that affects many functions of the nervous system. The symptoms and the severity of the disorder vary widely, al­though most patients experience a loss of sensation and numbness in the early stages, followed by progressive muscle weakness and difficulty walking. Although the disease tends to come and go, many patients eventually develop blurred or double vision, hearing problems, paralysis, and incontinence.

ParalysisThe inability to move one or more parts of the body is not a disease itself, but it may be caused by many of the conditions that cause numbness and loss of sensation. Paralysis may also result from a severe injury, such as a broken back or neck.

Peripheral neuropathyThis is a disorder in which one or more of the body's peripheral nerves become inflamed. It can be caused by a variety of other diseases and conditions, or by trauma. The most common symptom is pain that develops gradually, along with weakness, numbness, and tingling sensations in a specific area.

Pernicious anemiaThis is a chronic and progressive anemia caused by an inability to absorb, or a deficiency of, vitamin B-12. Numbness and tingling sensations in the hands and feet

are often early warning signs. Other symptoms include weakness and fatigue, breathlessness, lightheadedness, and pallor.

Stroke and cerebral hemorrhageNumbness and loss of sensation are major symptoms of a stroke, which may be caused by a blocked blood vessel in the brain or a cerebral hemorrhage, with bleeding into the brain. Such hemorrhages may be due to a ruptured blood vessel or a head injury. A cerebral hemorrhage may produce a sudden and severe headache, a stiff neck, labored breathing, nausea and vomiting, and loss of consciousness. Other stroke symptoms include loss of speech and motor control in part of the body, paralysis, or complete loss of sensation on one side of the body.

Spinal cord or disk disordersInjuries or disorders that affect the spinal cord, or the disks that act as shock absorbers between the spinal vertebrae, can cause numbness and loss of sensation. Some of these problems are not dangerous if properly treated. If, however, there is paralysis or loss of bladder and bowel control, immediate treatment is required.

Advice about numbness and loss of sensation

Momentary numbness or tingling sensations usually are not a cause for concern unless there are other symptoms.

The risk of back and neck injuries can be minimized by always wearing a seatbelt in a car and by using appropriate headgear for sports activities.

This article was last reviewed November 10, 2005 by Dr.
James Krider.Reproduced in part with permission of Home Health Handbook.